Enable moving files to folder IDs as well as names

[dtquandt]

Simple change which fixed an issue I was having (and which is currently mentioned in issue #46 ) where a folder cannot be found by name when using the move command but whose ID can be located with the gspread_pandas client or by examining the URL. This enables moving a file to a folder (using either client.move_file() or spread.move()) using its id, rather than its name. This is done with the id_string argument. When not explicitly using the id_string argument, it behavies identically to previous behaviour.

This is my first time contributing to open source, please forgive any mistakes in the process. Hope this helps!

[dtquandt]

I was unable to see what Better Code Hub complained about this PR as I do not have the required permissions. Please advise on any changes that must be made. Thanks!

[aiguofer]

Hi! I'm so sorry I hadn't gotten to this, I must have missed the e-mail notification about it (and I've been busy with a new job so I hadn't been checking the repo regularly). I'll try to take a look this week, and thanks so much for your contribution!

[benhoman]

Hi, I found this PR and this functionality would be quite useful to me. I made the changes that you suggested but I'm not really sure how to submit them to this existing PR but I also didn't want to just create a new one and add clutter. What would be the best/preferred way to handle this is?